Excessive engine oil comsumption, please help!

[andychen]

I am not a native-speaker so bare with m English.

Two months ago, I bought a 1999 corolla (80K miles). After some highway trips, I found that the engine oil was all gone at 800-mile point and the engine light was flashing. I had to add 3 quarts of oil to fill it up. The car run very smooth, engine was quiet before the oil pressure dropped very very low. It has great gas mileage (34 mpg on highway with AC on all the time). I did see some black residue on the bumper over the exhaust.

So I took it to a garage, the guy steam cleaned the engine, replaced PCV valve, spark plugs and service the throttle body. He said the oil pan gasket and valve cover gasket were leaking ($440 repair cost), but the leak was not severe and could not be the only reason for the excessive oil consumption. Then I took it to anther garage, the mechanic checked engine and found that there was some oil leaking, but not so much. He said if the engine is burning oil, it must be in pretty bad condition and car could not have such good gas mileage.

I then drove my car back at local for 300 miles, the oil level remained full. I then drove 200 miles on the highway and you know what, 1 quart of oil was used. I took the car to the second mechanic again, he let the engine run at very high speed and there was no white or blue smoke. He checked the spark plugs, and they were very clean. Again the car runs smooth and quiet, but one difference I noticed was the engine started to have noises when I went uphill at over 55 mph.

So what’s wrong with my car? Do I need to rebuild the engine or just trade in the car? Is my engine burning oil? How can I tell for sure?

Any suggestions are greatly appreciated.

[Copytech99]

Oil: Some 1ZZ engines consume oil. I think if you keep an eye on the oil level you should o.k.

Noise: My last 2 Corollas (91 & 00) both required 91 octane to prevent spiking and detonation from occuring during loads. ( I could get by with 87 in cool weather on my 00. It also consumed oil)

[andychen]

thanks, I have read some information about the engine, but those information still cannot explain the fact that the car did not lose any oil after 300 local miles and lost 1 quart after 200 highway miles.

[Huney1]

Originally Posted by andychen

thanks, I have read some information about the engine, but those information still cannot explain the fact that the car did not lose any oil after 300 local miles and lost 1 quart after 200 highway miles.

On the highway your engine is turning much faster and makes many thousands more revolutions than in town. The more revolutions the more oppurtunity it has to burn oil. There is a test called a compression check whereby they test each cylinder to see what the compression is and if one is way down then the rigns are probably worn. You said they didn't see any bluish smoke coming from the exaust indicating it isn't burning oil, or at least not so much that is is visible in the exhaust gases. You can check the spark plugs and if they're black with residue then that indicates burning oil that blew by the piston rings.

"He said the oil pan gasket and valve cover gasket were leaking ($440 repair cost), but the leak was not severe and could not be the only reason for the excessive oil consumption."

I think your problems is leaking rather than burning oil because the engine sounds pretty solid. I'd park it with a big piece of cardboard under the engine and let it sit over night and see how much oil leaked out.

Another thing. You didn't say how many miles on it but my guess is 100K miles or better in which case you should be using a 10W-30 oil especially if you live in a hot climate. Winter time cold weather cut back to a 5W-30.
Personally, if I had a cr with 100K and it ran as good as you say yours does then I wouldn't worry if it brunt a quart of oil every 500 miles because putting a quart of oil in it is one heck'ava lot cheaper than rebuilding the engine.

I'd like to share a well kept secret with you. http://www.marvelmysteryoil.com/ It is fantastic and I'd dump a pint in at your next oil change. As for your Enelish, . . . don't worry about it brother, I had no trouble understanding your question and if we can help more give a shout. Best to ya' and Happy 4th of July! God Bless America!

[jdmccright]

I'd do the compression check as Huney suggested. It's not hard and you can usually borrow the gauge from your auto parts store. Remember to pull off all the plug wires (or the coil-on-plugs) first...you just want to crank the engine over for a second or two to get your reading. Note the max pressures for each cylinder, they should be pretty close to each other +/- 15%. If one or more is noticeably low, pour a tbsp of oil in the plug hole and retest. If compression improves, the leaking is coming from worn piston rings. If not, it is due to worn valve stem seals.

Also as suggested would be to see where oil is coming out of bad seals by tracing oil drips from the bottom to the top. It helps to be able to power wash the engine (while it is cool!) to remove any built up grime & oil, then watch for fresh leaks.

Common leak areas are camshaft cover gasket, oil pan gasket, crankshaft/camshaft/oil pump seals (located under the timing belt cover), and less possibly the head gasket or rear crankshaft seal. Finally, if it is anything like the 2.2L 5s-fe engine, there are a couple of o-ring seals that are under the oil filter where it threads onto that have leaked oil for me once before. Good luck!